Monte Carlo Simulation of Fretting Wear Performance of Fuel Rods

The effect of the diverse parameters affecting the fretting-wear performance of nuclear fuel rods is investigated by performing Monte Carlo simulations with a fuel rod vibration model. The study is focused on the analysis of the effect of the grid parameters, including the cell clearance and the grid/support misalignments, on the support preload forces distribution, the rod dynamic response and the overall wear damage. In the present approach, the fuel rod and grids are modeled as a beam constrained at a finite number of axial positions and a non-linear vibration model is used to predict the rod motion and the wear rates. The results of the analysis suggest that an important fraction of the variability of the assembly wear damage distribution can be explained by the local variations of the rod-support conditions.